From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54AC0C4320E for ; Thu, 22 Jul 2021 22:09:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38F2360EB4 for ; Thu, 22 Jul 2021 22:09:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231910AbhGVV2u (ORCPT ); Thu, 22 Jul 2021 17:28:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231313AbhGVV2t (ORCPT ); Thu, 22 Jul 2021 17:28:49 -0400 Received: from mail-lf1-x12b.google.com (mail-lf1-x12b.google.com [IPv6:2a00:1450:4864:20::12b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E074AC061575; Thu, 22 Jul 2021 15:09:22 -0700 (PDT) Received: by mail-lf1-x12b.google.com with SMTP id q16so10799033lfa.5; Thu, 22 Jul 2021 15:09:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=sQcCO7T0VAeOgAPpjlMadGVJqKhrykjGpQRGvXrG7D4=; b=P9Ye/XTsfh014C3IkLuJWNzEvvbK5NNSjz9ggjj2gNq1gshduWRYIhCF9ETVibqLgf VUOYW7QWB0BjjkSn5AbCrOQNbD9ZIKHlpdqBHvpyDgyo+5YMUMp/zMNTs7Q0NGRkYmUn UydSeXEKwZEfSiLMUu3YT/kJERY1Xf5IAGg+uCgXSHZNYn8nFuLY82y1yU259oknri4f /cHM/1Mm07WZGR30SvqbasOvefUVihOjtIgxtZ63O+bik30eDhFg4s3SZ0SBBg0uczZt W17HyEPFGhdhC2Yz8/pADAbzaNwpobpWxWAhVec0q3nMI1iJji00nKG6c/V+CI6QfdxP Jdeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=sQcCO7T0VAeOgAPpjlMadGVJqKhrykjGpQRGvXrG7D4=; b=OUO77xb0ViRRe9mtXQWZ2HbTzccyui1qn8tYAgmtz6pSyU/mxHroFQKc0TRC4DD1Bg PL+LzkH83b8F1yktnVTsa1y9MmraW8otqS6xBxf4QbQsyfpd9PN/ioTvmScGGL/dhT3d jOxcHnkhVRTcCZyayVBID3dDInWeZcMRthRHtFbPxz0YocKhZ03f3jOyT2NpqcqClmJA keWiMaEUfCZ2QQzrbOIBrkQwf6azHa3LD82zSDiMiEhEe8n6RQl0PEuY88HdrmRzbZmU lNPpoc3tyMOqCF4IIiFx4pMcz47Bw+G7UbaRMq9qTt7jHbAPlWftTG6dOD/TQZD2LSHc iCHg== X-Gm-Message-State: AOAM530ahMVglekKeSoFxDPMOQMm/VHMYh9+qUotHxU+kF0jrVZod9uR LKOnuEXn5c4L2SDqKCRIbrw= X-Google-Smtp-Source: ABdhPJxSj5Qrch2X3G0CeHYQm8Cr6HGhrry0iOsxNObScS97gZBVYhJYtco3C8u1Bdcfc/l8coFAow== X-Received: by 2002:ac2:43a6:: with SMTP id t6mr980010lfl.194.1626991761252; Thu, 22 Jul 2021 15:09:21 -0700 (PDT) Received: from mobilestation ([95.79.127.110]) by smtp.gmail.com with ESMTPSA id g12sm3214158lja.13.2021.07.22.15.09.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jul 2021 15:09:20 -0700 (PDT) Date: Fri, 23 Jul 2021 01:09:18 +0300 From: Serge Semin To: John Stultz Cc: Bjorn Andersson , Krzysztof Kozlowski , Greg Kroah-Hartman , Rob Herring , Felipe Balbi , Florian Fainelli , Andy Gross , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-arm-msm , Linux USB List , lkml , linux-arm-kernel , Amit Pundir Subject: Re: [PATCH 29/29] arm64: dts: qcom: Harmonize DWC USB3 DT nodes name Message-ID: <20210722220918.l7j6zw3aaa27qato@mobilestation> References: <20210721100220.ddfxwugivsndsedv@mobilestation> <0064cb2c-5ca6-e693-2e89-8f045c8f7502@kernel.org> <20210721112531.xvu6ni5ksaehsrjh@mobilestation> <20210722181221.xh3r5kyu7zlcojjx@mobilestation> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 22, 2021 at 01:09:05PM -0700, John Stultz wrote: > On Thu, Jul 22, 2021 at 12:17 PM Bjorn Andersson > wrote: > > > On Jul 21, 2021, 1:45 PM +0200, Krzysztof Kozlowski wrote: > > > > I had impression that kernel defines interfaces which should be used and > > > > are stable (e.g. syscalls, sysfs and so on). This case is example of > > > > user-space relying on something not being marked as part of ABI. Instead > > > > they found something working for them and now it is being used in "we > > > > cannot break existing systems". Basically, AOSP unilaterally created a > > > > stable ABI and now kernel has to stick to it. > > > > > > > > Really, all normal systems depend on aliases or names and here we have > > > > dependency on device address. I proposed way how AOSP should be fixed. > > > > Anything happened? Nope. > > > > > > First time he sent a possible solution for the problem: > > > https://lore.kernel.org/lkml/20201221210423.GA2504@kozik-lap/ > > > > > > To sum up you could have used one of the more portable approaches > > > 1. add an udc alias to the controller and use it then to refer to the > > > corresponding USB controller > > > > Is there such a thing as "UDC alias"? Or are you suggesting that we > > should add such feature? > > > > I think it would be wonderful if we could identify the UDCs on our > > boards as "USB1" and "USB2", or "the one and only USB-C connector". But > > unless that will fall back to the existing naming it would break John's > > _existing_ userspace. > > Well, I'd not hold up the existing userspace I'm using as sacrosanct > (AOSP devices still usually don't have to work cross-kernel versions - > devboards being the main exception). I'm fine if we can rework > userland as proposed, so that the issues can be avoided, but I > honestly don't have enough context to really understand what that > looks like (no idea what udc aliases are). > > And whatever we do, the main constraint is that userland has to be > able to work with existing LTS kernels and newer kernels. As I said in my response to Bjorn even if it is added to the kernel it won't get to the official LTSes as it would be a new kernel feature. New features aren't normally backported to the older kernels. > > > > 2. search through DT-nodes looking for a specific compatible/reg > > > DT-properties. > > > > > > > We could define that this is the way, but again we didn't yesterday so > > your proposal is not backwards compatible. > > It may be backwards compatible, but I'm still not clear exactly how it > would work. > > I guess if we look through all > sys/bus/platform/devices/*/of_node/compatbile strings for the desired > "snps,dwc3", then find which of the directories have the desired > address in the string? (The suggestion for looking at reg seems > better, but I don't get a char value out of the dwc3 of_node/reg > file). The algorithm is simple: 1) You know what USB controllers you have on your platform. They are supposed to be compatible with snps,dwc3 string and have some pre-defined base address. 2) Find all the files in the directory /sys/class/udc/. 3) Walk through all the directories in /sys/bus/platform/devices/ with names found in 2) and stop on the device with matching compatible/base address defined in 1). In my case the strings could be retrieved like this: USB_NAME_COMPAT=$(/sys/bus/platform/devices/1f100000.usb/of_node/compatible | tr '\0' '\t' | cut -f1) USB_DEVICE_ADDR="$(head -c 4 /sys/bus/platform/devices/1f100000.usb/of_node/reg | hexdump -ve '/1 "%02x"' | sed -e 's/^0*//g')" Regards, -Sergey > > It seems much more straightforward to do an `ls /sys/class/udc/$GADGET_ADDR.*` > > But again, if folks decide the names can be rearranged to usb. > in the future, that would break too. > > thanks > -john